Concentric-pipe coil.



No. 79,201. PATENTED FEB. 18, 1908.

v 0.. S-EQNSSENBRENNBR.

OONGBNTRIO PIPE COIL.

APPLICATION FILED NOV. 28,1905.

I WITH E9565 lnvznnm (0 [Mm/a m ATTORNEY UNITED STATES PATENT, o FIcE.

CARL SENSSENBRENNER, OF OBE ROASSEL, NEAR DUSSELDORF, GERMANY, a

coNoEnTnIo-rmn coin.

, Specification of Letters Patent.

Patented Feb. 18, 1908.

Application filed November 28. 1905. Serial llo. 289.512.

To all whom it mar concern:

, Be 1t known that l, CARL SENSSENBREN- NEE, manufacturer, a sub ect oi Baden,

Grand Dukedom, Germany, residing at Obercasscl, near Dusseldorf, German Empire, have invented new and usei'ul l'IIlPIOV- ments in Concentric-Pipe Coils, of which the l l l l l 1 following is a specification.

lily invention has reference to'returnbend coils having concentric pipes, and relates in manner of ommg particular to an improved the pi ing at the bends. In t 1e construction oi return-bend coils of concentric pipes, the general practice is to employ connecting-caps, which screw on to the pipes, or are welded on, or are connected by special smiling-boxes. The objection to such methods of connection is that the outeraiae then )resents a number of )ro'ectin l 21 members, which prove disturbingin use.-

According to my invention I employ a bend conveniently welded to the outer pipe, so that the completed coil presents a thoroughly smooth surface throughout.

My invention is illustrated panying drawing, in which t Figure 1 is an elevation and part section of .a lat-return-bcnd coil of concentric pipes,

and Fig. 2'a'cross section taken through the line 1'1 o'l Fig. 1. V

The junction-piece b of the outer coil a is, at the actual bend, of oval cross section, of greater width than the external cross sec tion of the inner'pipc (Z- 0. Before welding the straight lengths a d to the bends 11 c, the

bends c of the inner coilare threaded through.

the oval sectioned bends b of the outer coil,

The bend a of the inner coil'canthen be welded on in the usual manner, since the outer bend I, owing to its oval cross section, can be drawn back so as to expose the places of welding e of the inner pipe.

After the welded "oints of'the inner coil have been inspected, the outer bends b can be pushed up to the ends of the outer straight sect-ions (I, and welded to them. 7

Any difl'erences in the circumference of the ends to be joined can be remedied on welding, so that the finished coil forms" a compact whole, the cross section of which changes Lug parts. 1

in the accom I l l .inopposite directions.

gradually, without there being any project- Instead of the bends I) being of oval cross section, any other suitable section may be adopted. In any case, however, the section must be such asto admit of the ends of the inner bonds 0 being sufficiently drawn out while, on the other hand, it must also allow of the bends bbeing brought close up again st the'ends of the outer pipe-sections to which they are to be welded. In this manner ins pection orrenewal of screw-caps and stuffingboxes, such" as is otherwisenecessary, is entirely avoided. The invention is particu-- larly applicable to condensers for liquefying the ammoniacal and carbo11ic acid vapors generated .in the, working of ice-making machinery; also to refrigerating apparatus for hqu ds; to heaters for llquids, when for the purpose of mutual transmission of heat and cold two liquids are conveyed in counter directions; and, further, to leedheaters in which the waterand waste-steam, for the purpose of utilizing the latter, are conducted Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A return-bend coil, comprising an inner convoluted pipe with. weldedon bends, and an outer convoluted pipe containing the same and having welded-on bonds of such bore that prior to welding they admit ol ample outward play of the inner-pipe bends within them, .for the purpose of enabling Welding of the latter to the abutting pipelengths, substantially as described.

,2; A return-bend coil, comprising an inner convoluted pipe with welded-cubends, and an outer convoluted .pipe containing the same and having welded-011 junction-pieces of oval section at the actual bend, so that prior to weldingthey'adrnit of ampleoutward play ofthe innerpipe bendswithin'thenn 'for the pur mse of enabling welding of the 

